Method of making propellent powder



ED a ans PATENT uric.

RICHARD GEORGE WOODBRIDGE, JR., OF WILMINGTON, DELAWARE, ASSIGNOR TO E. I. DU PONT DE NEMOURS &, COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE.

METHOD OF MAKING PROPELLENT POWDER.

No Drawing.

To all whom it may concern:

Be it known that I, RICHARD G. 7001)- BRIDGE, J r.,of Wilmington, in the county of New Castle, and in the State of Delaware, have invented a certain new and useful Improvement in Methods of Making Propellent Powder, and do hereby declare that the following is a full, clear, and exact description thereof.

My invention relates to a process of producing explosives of an advantageous character, and more particularly, however, to the production of propellent powders of the progressive type, that is to say, which are so treated as to provide a lower initial pressure without reducing the Velocity of the projectile. My invention is applicable to the various kinds of rifle and cannon powders.

The object of my invention is to provide a process of producing powders of this type which do not have the disadvantage of previous processes of producing powders containing coatings on the outside thereof but not impregnating the surface of the same, that is to say, the great difliculty of ignition which often resulted in hang fires.

Another object of my invention is to provide a process by which a powder is obtained which will produce considerably less erosion in rifle linings than previous powders.

A further object is to provide a process by means of which the surface of the powder grains may be effectively impregnated with a mixture of deterrent explosives or deterrent materials which are not explosives or mixtures of these classes of substances, and in such a manner that the grains are prevented from adhering to one another, as well as to secure more uniform impregnation of the grains by the coating materials than hitherto.

The object of my invention is especially to provide a process by meansof which deterrent explosives and deterrent materials that are not explosive, which, because of their low volatility and good stability, as well as other properties would be sultable for surface impregnation of the smokeless powder grains, but which have such high melting points that they could not be used alone to impregnate the surface of the pow-v der grains because such high temperature would affect the stability of the powder,

Specification of Letters Patent.

Application filed August 17, 1918.

Patented Aug. 5, 1919.

Serial No. 250,330.

can be used in mixtures because of the fact that such mixtures have lower melting points than the constituents of such mixtures, and can be applied at even lower temperatures than the melting points of the mixtures with the aid of hot water, as the presence of the water causes such mixtures to melt below the temperatures at which such mixtures would otherwise melt.

The object of my invention is furthermore to provide a process which is an improvement over the process as set forth in the application of Alfred L. Broadbent and myself upon the process of making propellent powder, Serial No. 109,249, filed July 14:, 1916. I

Further objects of my invention will appear from the detailed description thereof contained hereinafter.

While my invention is capable of embodiment in many different forms, for the purpose of illustration I shall describe only certain ways of carrying out my invention hereinafter.

For example, 100 parts by weight of nitrocellulose powder grains are introduced into a revolving mixing drum of any desiredv character, which may or may not be provided with longitudinally directed ribs on the interior cylindrical surface. Thereafter, I introduce into the drum 3 parts by weight of a mixture of 75 parts by weight of dimethyldiphenylurea and parts by weight of dinitrotoluene, after which the entire mass is covered with water. The dimethyldiphenylurea and dinitrotoluene may be added in the drum separately, or may be previously mixed before introduction into the drum. The dimethyldiphenylurea may be practically pure having a melting point between 120 and 121 C., but preferably I use a commercial dimethyldiphenylurea containing some impurities, and melting at about 110 ,C. or over. The dinitrotoluene may be one of several isomers, or a mixture of the same obtained by the direct nitration of toluene but I prefer to use pure dinitrotolue-ne, that is to say, 121 dinitrotoluene. After the materials in the drum have been thoroughly mixed, that is to say in from five to ten minutes, heat is applied in any suitable manner as by injecting steam into the drum or into a acket thereon, while the temperature is gradually raised to 80 C. This will be sufiicient in the presence of the water to melt the dimethyldiphenylurea and dinitrotoluene. Inasmuch as the dimethyldiphenylurea and dinitrotoluene, either alone or when mixed together are solvents of nitrocellulose, they colloid the nitrocellulose and impregnatethe surface of the grains. The temperature of 80 C. is maintained for about thirty minutes, as this is usually sufficient to impregnate the powder with the mixture of dimethyldiphenylurea and dinitrotoluene, and to cause the latter two sub stances to disappear. However, the impregnation is not complete in this period of time, and in order to complete the impregnation of the powder grains the materials are removed to a stationary tank of hot water at 80 (1, where they remain for a period amounting approximately to twentyfour hours. After this the powder grains are removed and dried. The impregnation is completed in this manner and at the temperature referred to notwithstanding the fact that the dimethyldiphenylurea and dinitrotoluene of the grades used might melt for example at 115 and 68 (1, respectively, and notwithstanding the fact that a mixture of 75 parts by weight of dimethyldiphenlyurea and 25 parts by weight of dinitrotoluene have a melting point of approx1- mately 92 to 104 (1, depending upon the purity of the constituents.

A nitrocellulose powder before having been impregnated as above will give in a military rifle a muzzle velocity of 2,700 feet per second and a mean pressure or 49,000 pounds per square inch, with a charge weighing forty-five grains, while a sample of the powder impregnated as above,

-will give the same muzzle velocity with a mean pressure of only 40,000 pounds per square inch, with a charge weighing 46.6 grains. The difference in the erosive effect of the two powders is even more marked, as

the erosion by the impregnated powder is only one-fourth to one-third that of the powder Which has not been impregnated.

The proportions in the above mixture may be varied through wide limits. For example, three parts by weight of a mixture of dimethyldiphenylurea and dinitrotoluene may be used, but any amount varying from one to ten parts by weight may be used according to the ballistic results desired. Furthermore, the proportion of parts by weight of dimethyldiphenylurea to 25 parts by weight of dinitrotoluene is not essential, but may be varied. Again when difi'erent mixtures are used, different temperatures will also be used. If for example, a, mix- 1 ture of 50parts by weight of dimethyldi phenylurea and 50 parts by weight of dinitrotoluene are used, a temperature of 70 (1, will be applied. Furthermore, if the proportion of dimethyldiphenylurea is increased, the temperature will be accordingly increased. In fact, I have found that any mixtures of the above character which in the presence of hot water do not have a melting point above 100 (1, may be used in my process for impregnating the surfaces of the nitrocellulose powder grains.

Again it will be understood that other deterrent materials whichare not explosive, and which are substantially insoluble in water, may be used instead of the dimethyldiphenylurea, as for example, phenylacetanilid, and that instead, I may use mixtures of two or more such deterrent materials. Furthermore, instead of the dinitrotoluene I may use some other deterrent explo- 'sive which is substantially insoluble in water, such as mononitrotoluene, or a mixture of two or more such substances. Again I might use any mixture or mixtures of deterrent materials that are not explosive With deterrent explosives, which in the presence of hot water melt at a temperature below 100 0.

While I have described my invention above in detail, I wish it to be understood that many changes may be made therein without departing from the spirit of the invention.

I claim:

1. The process which comprises impregnating the surface of an explosive grain 1nsoluble in water with a mixture of deterrent -m=aterials substantially insoluble in. water by subjecting the grain, while intimately mixed with said deterrent materials, to treatment with hot water.

2. The process which comprises impreg na-tin the surface of an explosive grain in solub e in water with a mixture of deterrent materials having a melting point below (1, substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent materials, to treatment with hot water.

3. The process which comprises impreg nating the surface of an explosive grain insoluble in water with a mixture of deterrent materials, one of which is GXIPlOSlVG,2LI1d one of which is not explosive, substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent materials, to treatment with hot water.

4. The process which comprises impregnating the surface of an explosive grain insoluble in water with a mixture of deterrent materials comprising dimethyldip-henylurea and dinitrotoluene, substantially insoluble in water, by subjecting the grain,- while intimately mixed with said deterrent materials, to treatment with hot water.

5. The process which comprises impregnating the surface of an explosive grain in soluble in water with a mixture of deterrent materials comprising dimethyldiphenylurea ene, substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent materials, to treatment with hot water.

6. The process which comprises impregnating the surface of an explosive grain insoluble in water with a mixture of deterrent materials substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent materials, to treatment with 'hot Water, at a t mperature below the melting point of the mixure of deterrent materials.

7. The processwhich comprises impregnating the surface of an explosive grain insoluble in water with a. mixture of deterrent materials having a melting point below 100 0., substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent materials, to treatment with hot water, at a temperature below the melting point of the mixture of deterrent materials.

8. The process which comprises impregnatln the surface of an exploslve gram 1nsolub e in water with a mixture of deterrent materials, one-of which is explosive, and one of which is not explosive, substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent materials, to treatment with hot water, at a temperature below the melting point of the mixture of deterrent materials.

'9. The process which comprises impregnating the surface of an explosive grain insoluble in water with a mixture of deterrent materials comprising dimethyldiphenylurea and dinitrotoluene, substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent materials, to treatment with hot water, at a temperature below the melting point of the mixture of deterrent materials.

10. The process which comprises impregnating the surface of an explosive grain insoluble in water-with a mixture of deterrent materials comprising dimethyldiphenylurea and substantially pure1-2--4 dinitrotoluene, substantially insoluble in water, by subjecting the grain while intimately mixed with said deterrent materials, to treatment with hot water, at a temperature below the melting point of the mixture of deterrent materials.

11. The process which comprises impregmating the surface of a nitrocellulose powder grain insoluble in water with a mixture i of deterrent materials substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent materials, to treatment with hot water, at a temperature below the melting point of the mixture of deterrent materials.

12. The process which comprises impregnating the surface of a nitrocellulose powder grain insoluble in water with a mixture of deterrent materials having a melting point below 100 (3., substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent materials, to treatment with hot water, at a. temperature below the melting point of the mixture of deterrent materials.

13. The process which comprises impregnating the surface ofa nitrocellulose powder grain insoluble in water with a mixture of deterrent materials, one of which is explosive, and one of which is not explosive, substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent hot water, at a temperature below the meltingl point of the mixture of deterrent materia s.

14. The process which comprises impregnating the surface of a nitrocellulose powder grain insoluble in water with a mixture of deterrent materials comprising dimethyldiphenylurea and dinitrotoluene, substantially insoluble in water, by subjecting the grain, while intimately. mixed with said deterrent materials, to treatment with hot water, at a temperature below the melting point of the mixture of deterrent materials.

15. The process which comprises impregnating the surface of a nitrocellulose powder grain insoluble in water with a mixture of deterrent materials, comprising dimethyldiphenylurea and substantially pure 1-24= dinitrotoluene, substantially insoluble in water, by subjecting the grain, while intimately mixed with said deterrent materials, to treatment with hot water, at a temperature below the melting point of the mixture of deterrent materials.

In testimony that I claim the foregoing and have hereunto set my hand.

RICHARD GEORGE WOODBRIDGE, JR. Witnesses:

G. D. HOPKINS, STANLEY L. ABRAMS.

materials, to treatment with 

